practical sysml applications: a method to describe the ... · pdf file... describe the...
TRANSCRIPT
![Page 1: Practical SysML Applications: A Method to Describe the ... · PDF file... Describe the authority of the stakeholder in each of ... requirement as the diagram is built ... – Object](https://reader033.vdocuments.us/reader033/viewer/2022051722/5aa4a6507f8b9a185d8c4eee/html5/thumbnails/1.jpg)
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Practical SysML Applications: A Method to Describe the Problem Space
Ray Jorgensen
David Lempia
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2
Originating Customer Requirements
• Answer the questions:
– What is the problem?
– What are the users doing?
– What are the objects in the real world?
• Work from the user requirements inward
• Ends with requirements review
– Vocabulary consistent between domain model, requirements, and use cases
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Roles: Describe the role the stakeholder plays. There may be
more than one role each stakeholder operates in.
Authority: Describe the authority of the stakeholder in each of
their roles.
Knowledge: Describe the level of knowledge the stakeholder
has.
3
Stakeholder needs
1) Identify stakeholders
2) Describe stakeholders
3) Identify Stakeholder Needs
Commander
SoldierMaintenance
Application Dev eloper
«is-a»
Commander
Soldier
Maintenance
Application Dev eloper
Receive mission updates
Send command to one or more
soldiers
Send message without sound
Receive messages without making
noise
Create new applications
SW development kit
Update software on units in service
«express»
«express»
«express»
«express»
«express»
«express»
«express»
«express»
«is-a»
4) Add need necessity & rational
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Source Requirements
• Study in the application of SysML concepts to avionics development and TCP workflow
– INU Update:
• 3.2.1.8 Weather Radar
• The existing weather radar system SHALL be integrated into the flight deck and provide control for skin-paint, ground mapping, and INU update functions to pilot, co-pilot, and navigator stations.
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Capture Architectural Context
• Show actors and association with system of interest
• Purely “black box” perspectives
bdd Operational Context
<<block>>
Nav Solution
Update System
Operator
<<block>>
Fixed Reference
<<block>>
Cartographic
Reference
2 2
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Operational Concepts
• Start with functional requirements and stakeholder needs
• Create a satisfy trace to each activity/action generated from a functional requirement as the diagram is built
• Re-use actors and external systems from the stakeholders and architecture context packages
– If you discover a new actor or system, add it to the stakeholder/architecture context also
6
Create Use Case Diagram
Bring in actors, system,
and external systems from
originating requirements
package
Create use case. Fill in
notes and tags.
Fill in textual stepsCreate activ ity diagram
below use case
Phase 1 - Add activ ities
the primary actor performs
Phase 2 - Add activ ities
the system and other
external systems perform
Phase 3 - Add data items
flowing between
swimlanes
Identify exceptions
(failure) and alternate
courses for each activ ity
[Complex][Simple]
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«Main_Course»
Send hand gesture
message
«Exception»
Unrecognized gesture
Soldier
(from Stakeholder Needs)
«System»
Architectural Context::
Gesture Radio
«Alternate_Course»
Cancel and resend
message
«primary» «extend»
«extend»
Use Case Diagram
Block – My system or other systems
Actor Use Case
Stereotype
Association
Dependency (extend/include)
Composite
(Use Case Diagram)
(Activity Diagram)
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Conduct Use Case Analysis
• Identify prospective Use Case: “verb-noun” convention
• Primary actor identification
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Characterize Use Case
• Purpose, Goal, or Objective
• Trigger Stimulus
• Preconditions
• Post Conditions
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Build Activity Diagram (Scenario)
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Define Scenario
• Add activities of primary actor
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Define Scenario
• Add Activities of system of interest and other supporting actors
• Maintain purely “black box” perspective
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Organize Model Elements
• Activity Diagrams (Scenarios) under Use Case elements
• Make Use Case “composite” – double click opens scenario
uc Update from WXR Source
AC: Update from WXR
Source
Operator
(from Architectural Context)
<<block>>
Architectural
Context::Nav
Solution Update
System
<<block>>
Architectural
Context::Fixed
Reference
<<block>>
Architectural
Context::
Cartographic
Reference
EX: Unable to select
location ov er WXR
image
AC: Enter manual
checkpoint
AC: Select
checkpoint from
listing (future)
AC: Select
checkpoint from
cartographic image
(future)
EX: Incomplete update fix
reference
EX: No WXR Image
Av ailable
<<extend>>
<<extend>>
<<extend>>
<<extend>>
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Add Exceptions and Alternate Courses
• Examine each “happy day” step (activity)
• What can go wrong?
• What else might the actor do?
• Does the step itself require further elaboration (extension)?
• Simple dependency relationship from activity to use case
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Use Case Extensions
• Add:
– Alternate Courses
– Exceptions Cases
– Extensions
• Maintain singular focus
– One use case is primary focus of Use Case Diagram
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Elaborate Each Extension
• Activity diagram (scenario) for each AC or EX
• May be variant of original use case scenario
act Update from Ov erfly Reference
the :Nav Solution Update Systeman :Operator
Select update source for
fixed reference
Freeze the nav igation
solution(s)
Accept the update to the
degraded nav igation
solution
Prov ide update fix
reference
Calculate update v ector
Apply update
AC: Update from ov erfly reference
notes
Purpose:
To update a navigation solution with a reference point that the aircraft overflies.
Trigger Stimulus:
Pilot desires to update nav solution with a fix reference visual overflight.
Preconditions:
The navigation solution has reached a degraded state with no automatic updates from fixed reference
sources. Update page is already being displayed.
Post Conditions:
The degraded navigation solution is now providing present position estimates with the update correction.
ActivityInitial
ActivityFinal
Enter reference fix
coordinates
Display Ov erfly Update
A
Pilot manually steers aircraft
toward reference fix. Select
Freeze only when aircraft
overfl ies the reference fix.EX: Select Nav igation
Solution to Upgrade that is
Inv alid
EX: Select Valid
Nav igation Solution
(Not Degraded)
Determine Estimated
Position
EX: Select Update
Source that is Inv alid
EX: Enter Inv alid
Position
AC: Freeze Update
Solution with Control
Wheel Selection
EX: Clear Update
Bias
Navigation Solution =
Invalid
[Update Fix Reference =
Invalid]
Reset Bias
[Update Fix Reference = Valid]
Update Fix Reference =
Invalid
Navigation Solution = Valid
[Update Acceptance = Accept]
[Update Source Select = OVERFLY]
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act Update from WXR Source
an :Operator the :Nav Solution Update System
Select update source for
fixed reference
Prov ide update fix
reference
Adjust WXR image of the
selected targetProv ide image of WXR
target
Select checkpoint
reference from
cartographic reference
Select location of WXR
target image
Accept the update to the
degraded nav igation
solution
Apply update
Note: Since no entries
provided, yet, all
references shown
invalid.
EX: Unable to select
location ov er WXR
image
AC: Enter manual
checkpoint
EX: Incomplete update fix
reference
EX: Select Nav igation
Solution to Upgrade that is
Inv alid
Calculate update v ector
AC: Update from WXR Source
notes
Purpose:
To update a navigation solution with a fix from a known reference using a weather range/ bearing to the fixed object..
Trigger Stimulus:
Pilot desires to update nav solution using a weather radar fix on the object..
Preconditions:
The navigation solution has reached a degraded state with no automatic updates from fixed reference sources. Update page is
already being displayed.
Post Conditions:
The degraded navigation solution is now providing present position estimates with the update correction.
Display WXR Update
ActivityInitial
ActivityFinal
Determine Estimated
Position
AC: Select
checkpoint from
cartographic image
(future)
AC: Select
checkpoint from
listing (future)
EX: No WXR Image
Av ailable
EX: Enter Inv alid
Position
EX: Clear Update
Bias
Navigation Solution = Invalid
Reset Bias
[Update Acceptance = Accept]
[Update Fix Reference = Valid]
[Update Source = WXR]
![Page 18: Practical SysML Applications: A Method to Describe the ... · PDF file... Describe the authority of the stakeholder in each of ... requirement as the diagram is built ... – Object](https://reader033.vdocuments.us/reader033/viewer/2022051722/5aa4a6507f8b9a185d8c4eee/html5/thumbnails/18.jpg)
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Scenario Diagrams
• Generally, use Activity Diagrams to express unique scenarios
• However, if alternate course or exception is “simple”, consider “Notes” narrative
• Use Case Analysis generates future opportunities – capture them!
![Page 19: Practical SysML Applications: A Method to Describe the ... · PDF file... Describe the authority of the stakeholder in each of ... requirement as the diagram is built ... – Object](https://reader033.vdocuments.us/reader033/viewer/2022051722/5aa4a6507f8b9a185d8c4eee/html5/thumbnails/19.jpg)
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Repeat Use Case Process
• 1) Use Case identification
• 2) Scenario definition – primary actor
• 3) Scenario definition – system of interest, seconday actors
• 4) Consider alternate courses/ exceptions/ extensions
uc Update from WXR Source
AC: Update from WXR
Source
Operator
(from Architectural Context)
<<block>>
Architectural
Context::Nav
Solution Update
System
<<block>>
Architectural
Context::Fixed
Reference
<<block>>
Architectural
Context::
Cartographic
Reference
EX: Unable to select
location ov er WXR
image
AC: Enter manual
checkpoint
AC: Select
checkpoint from
listing (future)
AC: Select
checkpoint from
cartographic image
(future)
EX: Incomplete update fix
reference
EX: No WXR Image
Av ailable
<<extend>>
<<extend>>
<<extend>>
<<extend>>
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Add Object Flows
• Add object flow for each interaction
• Two activity diagrams:
– Sequence flow of scenario
– Object flow of scenario
• However:
– Consider transaction “visibility” between actors (swimlanes)
– Consider activity hierarchy (functional decomposition)
![Page 21: Practical SysML Applications: A Method to Describe the ... · PDF file... Describe the authority of the stakeholder in each of ... requirement as the diagram is built ... – Object](https://reader033.vdocuments.us/reader033/viewer/2022051722/5aa4a6507f8b9a185d8c4eee/html5/thumbnails/21.jpg)
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Activity Hierarchy
• Functional Decomposition
– Similar to typical requirements document outline?
bdd Logical Hierarchy
Manage Human Machine
Interface
Display Nav Solution Page
Display Update Page
Compute Nav igation
Solution
Update Nav igation
Solution
Prov ide update fix
reference
Determine Estimated
PositionCalculate update v ector Apply update
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Objects Flows: Data Dictionary
• Manage object flow in a data dictionary
– Create types, generalizations
• Manage object flow “instances” vs. “building block” types
• Characterize interface requirements
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Object Flows: Data Dictionary Diagrams
bdd Data Types
<<block>>
Freeze Select
<<block>>
Update Accept
Select
<<block>>
Update Fix
Reference<<block>>
Update Page
Select
<<block>>
Update Vector
<<block>>
User Select Entry
<<block>>
Position
<<block>>
Vector
Real Data Item
<<block>>
Latitude
Real Data Item
<<block>>
Longitude
Real Data Item
<<block>>
Altitude
Real Data Item
<<block>>
Bearing
Real Data Item
<<block>>
Distance
Data Item
<<block>>
Enumerated Data
Item
Data Item
<<block>>
Compound Data
Item
<<block>>
Update Source
Select
<<block>>
Estimated
Position
<<block>>
Av ailable Nav
Solutions
<<block>>
Update Reject
Select
<<block>>
Integrated Nav
Solution Select
<<block>>
Updating Solution
<<block>>
Update Bias Clear
Select
<<block>>
Page Return
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Logical Architecture – Composite Views of ALL Interactions
act Update Nav igation Solution
fix :Update Fix
Reference
cursor :
Position
control :
Freeze
Select
Update Nav igation Solution
fix :Update Fix
Reference
cursor :
Position
control :
Freeze
Select
Apply update
Calculate update v ector
computed :Update
Vector
estimate :Estimated
Position
fix :Update Fix Reference
provided :Updating
Solution
selected :Update
Source Select
selected :Available Nav
Solutions
selected :Freeze Select
selected :Update Accept
Select
selected :Update
Reject Select
entered :Update Fix
Reference
Display Update Page
computed :Update
Vector
estimate :Estimated
Position
fix :Update Fix Reference
provided :Updating
Solution
selected :Update
Source Select
selected :Available Nav
Solutions
selected :Freeze Select
selected :Update Accept
Select
selected :Update
Reject Select
entered :Update Fix
Reference
Prov ide update fix
reference
solution set :Navigation
Solution Set
applied :Update Vector
Compute Nav igation
Solution
solution set :Navigation
Solution Set
applied :Update Vector
computed :Update
Vector
(from Instances)
control :Freeze
Select
(from Instances)
estimate :
Estimated Position
(from Instances)
reference :Update
Fix Reference
(from Instances)
Determine Estimated
Position
cursor :Position
(from Instances)
Determine Cursor Location
Plan Flight RouteActiv e :Waypoint
(from Instances)
fix :Update Fix
Reference
(from Instances)
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act Display Update Page
display :Update Page
Display Update Page
display :Update Page
Compute Nav igation
Solution
Display Nav Solution Page
display :Update Page
(from Instances)
entry :Update Page
Select
(from Instances)
Display Ov erfly Update
A
Display Integrated Nav
Solutions
Display WXR Update
config :Av ailable Nav
Solutions
(from Instances)
fix :Update Fix Reference
computed :Update Vector
selected :Update Accept Select
selected :Update Source Select
selected :Freeze Select
estimate :Estimated Position
selected :Available Nav
Solutions
selected :Update Reject Select
selected :Updating Solution
entered :Update Fix Reference
Update Nav igation Solution
fix :Update Fix Reference
computed :Update Vector
selected :Update Accept Select
selected :Update Source Select
selected :Freeze Select
estimate :Estimated Position
selected :Available Nav
Solutions
selected :Update Reject Select
selected :Updating Solution
entered :Update Fix Reference
entry :Update Source Select
(from Instances)
entry :Av ailable Nav Solutions
(from Instances)
entry :Update Fix Reference
(from Instances)
entry :Freeze Select
(from Instances)
entry :Update Accept Select
(from Instances)
entry :Update Reject Select
(from Instances)
display :Update Vector
(from Instances)
display :Estimated Position
(from Instances)
display :Nav Solution
Page
(from Instances)
display :Update Fix Reference
(from Instances)
display :Av ailable Nav Solutions
(from Instances)
entry :Update Bias Clear Select
(from Instances)
selected :Update Bias Clear Select
(from Instances)
[Update Source Select = OVERFLY]
[Update Source Select = WXR]
[Update Source Select = NAV]
[activate]
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Further Consideration
• When to use Actions vs. Activities
• Object Flows vs. Object Nodes
• Extended scenarios – from “black box” problem space into “white box” solution space
• Functional Allocation
– “Allocate” relationship vs. Tagged Value “Relationship”
– Inheritance through instantiation
• Interface Allocation
– Object Flow/ Data Item allocation to Software Data Stream messages
– Object Flow allocation to Human Machine Interface
![Page 27: Practical SysML Applications: A Method to Describe the ... · PDF file... Describe the authority of the stakeholder in each of ... requirement as the diagram is built ... – Object](https://reader033.vdocuments.us/reader033/viewer/2022051722/5aa4a6507f8b9a185d8c4eee/html5/thumbnails/27.jpg)
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Contact Information
Raymond W. Jorgensen
Rockwell Collins
MS 108-265
400 Collins Rd NE
Cedar Rapids, IA 52498
(319)295-2615